What Are the Difference Between Foam Rubber and Sponge Rubber?

Foam rubber and sponge rubber are both types of absorbent materials. While they are similar in some ways, they also have some differences. Foam and sponge rubber have different characteristics, such as density, color, and odor. Comparing the two can aid in understanding their uses and benefits so that users can decide which best suits their needs.


The article provides a deeper insight into the difference between foam rubber and sponge rubber. It also gives a broad idea about the applications of these industrial rubber products in various industries.

Heating temperature

As the presence of foaming agents characterizes foam rubber, the heating temperature of this material may be affected by the type, amount, and concentration of these additives. The maximum temperature of a sponge rubber sample depends on its composition, precisely the amount of carbon in the model. Lighter samples are less thermally conductive than heavier ones due to their lower density. Thus, when a heavy foam rubber sample is placed directly against a carbon-infused foam rubber (one with a much higher heat transfer coefficient), their heated surfaces will form what appears to be an insulating layer that separates them and keeps them safe from each other.

Density and elasticity

The density of sponge rubber is one-third that of foam rubber. This can be attributed to sponge rubber being composed of organically-derived materials, while foam rubber is composed of petroleum-derived materials. As mentioned before, the elasticity of both foams and sponges is entirely different. Sponge rubber has a high elasticity because its plies are interconnected. On the other hand, foam rubber has a low elasticity due to numerous links between its plates.

Chemical properties

Sponge rubber is a polymer composed of liquid monomers and then polymerized. The degree of polymerization (DP) of the sponge rubber is controlled by the type, quantity, and temperature of the monomers used to produce the polymer. The properties of a sponge rubber depend on the type and structure of its molecular chains. Lower DP polymers have a more flexible molecular structure than any other polymers because they have a single chain that can expand or contract without breaking into smaller units.

The chemical properties of foam rubbers can be described as a class of high molecular weight polymeric substances that have a soft, flexible, resilient character and can be molded into various shapes. Foam rubber is composed of many different types of molecules which exhibit vastly different physical properties depending upon their composition. These properties include elasticity, Young’s modulus, hardness, and tensile strength. Many other compounds are used to make foam rubber, ranging from petroleum gum-derived materials to synthetic compounds from petroleum-based materials.


Foam rubber is a commonly used material that is non-toxic. The foam rubber industry has invested money into developing friendlier, less harmful products so that workers can be assured of not being exposed to poisonous fumes or vapors when working with these materials. Foam rubber is a synthetic material that consists of polyethylene oxide (PEO) and polyvinylidene phthalate (PVdC) matrix. These materials have been used for many years as highly gas resistant and durable due to the replacement of carbon monoxide with nitrogen in the polymerization process. This new gaseous mixture does, however, cause health effects, including respiratory tract irritation and skin sensitization.

Sponge rubber is a biopolymer with a unique molecular structure, which makes it toxic:

  • It may act directly on the nervous system at 14 to 32 degrees Celsius. Because of this, sponges are used in classrooms to teach children about science.
  • Sponge rubber can be absorbed in situ by inhalation when exposed to a small quantity (1/3 gram per square meter) and, because of its low melting point (30°C), into some fibers and fabrics of clothing, furniture, and so on.
  • Sponge rubber is also a strict contact sensitizer with any parts of the skin exposed to it, and by inhalation; it acts similarly to latex and other severe allergies that are sensitive due to blood groups.

Differences in their uses

Foam rubber is used to seal or protect an opening or a hole. It can create a seal between two objects, like between a lid and a bowl. As it is soft and compressible, it can also be molded into shapes like balls, tubes, and cups. Foam rubber doesn’t smell like other products in its family (latex), so it can be used for medical applications such as bandages. In this application, the product absorbs moisture from moist air inside the packaging, which helps keep it fresh for extended periods.

Sponge rubber can be used as a cushion, insulator, and scraper. Sponge rubber is made from natural or synthetic rubber or a combination of both. The most common type of sponge rubber is hyaline, with an average thickness between 300 – 400 microns. Sponges are frequently used in various industries, including transportation, foodstuff, and pharmaceutical industries. Sponges are also used for industrial applications, such as disposable hand-washing sponges, which can absorb water and dry more quickly than other materials, making them ideal for use where quick dryness is required. They are widely used in the aircraft industry to protect avionics equipment from corrosion caused by moisture.

Sponge rubber and foam rubber have many advantages over each other. Both have their advantages and disadvantages in different areas of use. In some cases, one type of rubber may be better. However, both are used extensively by industrial rubber manufacturers.

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